Active set update (asu) with high speed downlink shared channel (hs-dsch) information

ABSTRACT

Because the current RRC: ACTIVE SET UPDATE message presently used in soft handover does not contain HS-DSCH related information, which could be utilized for a Serving HS-DSCH cell change, a separate Radio Bearer Control procedure is needed between the UE (10) and the RNC (20) for carrying out the Serving HS-DSCH cell change. Should HS-DSCH related information—applicable to Serving HS-DSCH cell change—be added to the RRC: ACTIVE SET UPDATE message (32), an unnecessary Radio Bearer Control procedure is avoided, and the drawbacks of the current method are overcome.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of application U.S. patentapplication Ser. No. 11/237,643, filed Sep. 27, 2005, which in turnclaims priority from U.S. Provisional Application Ser. No. 60/614,562filed Sep. 29, 2004.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates to handover mechanisms for mobile radiodevices and, more particularly, to simplifying signaling used to carryout a change in a serving High Speed Downlink Shared Channel (HS-DSCH)cell change.

2. Discussion of Related Art

The Third Generation Partnership Project (3GPP) Release 5 (Re15)introduced a new HS-DSCH transport channel.

From the 3GPP Release 6 Technical Specification TS 25.308 v6.1.0(2004-03), it is set forth in Chapter 9 that mobile evaluated handovermechanisms provide the Radio Resource Control (RRC) connection mobilityin a CELL_DCH state (see 3GPP TS 25.331 v6.2.0 (2004-06) Chapter 7.1 foran overview of the RRC states and state transitions including GSM). Themobility procedures are affected by the fact that the High SpeedPhysical downlink shared channel (HS-PDSCH) allocation for a given userequipment (UE) belongs to only one of the radio links assigned to theUE, the serving HS-DSCH radio link. The cell associated with the servingHS-DSCH radio link is defined as the serving HS-DSCH cell.

When conditions for an Active Set Update (ASU) (see 3GPP TS 25.331v6.2.0 (2004-06) Release 6, Chapter 8.3.4 Active Set Update) and ServingHS-DSCH cell change (see 3GPP TS 25.308 v6.1.0 (2004-03) Release 6,Chapter 9, Mobility Procedures) become simultaneously effective, i.e.when the serving HS-DSCH cell operation is to be moved to the otheractive set cell and active set of the UE is to be modified (adding newcell (1A), or replacing existing cell with new one (1B), RRC proceduresinvolved (Active Set Update (ASU) and Radio Bearer Control) must beperformed separately, one after the other. Depending on scenario eitherthe ASU or Radio Bearer Control procedure is performed first. If the ASUis performed first, the Radio Bearer Control Procedure is delayedintroducing performance degeneration to HS-DSCH transmission, which cancritical for maintaining the connection, especially when SRBs are mappedon HS-DSCH (required when introducing Fractional DPCH). In otherscenario, the Radio Bearer Control procedure containing the necessaryHS-DSCH information is needed to be performed first followed by ASU, dueto fact that current serving HS-DSCH cell needs to be removed from theUEs AS before RNC is able to add new cell to the AS. This introduces arather long delay for the ASU, potentially risking the connection. Insome cases this delay could not be tolerated and ASU has to be performedfirst causing a rather long break in HS-DSCH transmission instead.

DISCLOSURE OF INVENTION

According to a first aspect of the present invention, a method forexecution in a radio network controller comprises receiving at the radionetwork controller a measurement report from a user equipment, making adecision at the radio network controller to make a serving high-speeddownlink shared channel cell change and to make an active set update,preparing a radio link at a new cell to operate as a serving high-speeddownlink shared channel radio link, sending an active set update messagefrom the radio network controller to the user equipment, said active setupdate message including information about the high-speed downlinkshared channel cell change, receiving at the radio network controller anactive set update complete message from the user equipment, and startinga frame protocol in the radio link of the new cell. A computer programmay be provided stored on a computer readable medium for execution ofthe foregoing steps.

According to a second aspect of the present invention, a method forexecution in user equipment comprises receiving an active set updatemessage from a radio network controller with a radio link addition orremoval to or from the active set, or both, checking the active setupdate message for information about a serving high-speed downlinkshared channel cell change, configuring the user equipment to operatewith a new serving high-speed downlink shared channel cell, adding orremoving, or both, a radio link to or from, or both, an active set, andsending an active set update complete message from the user equipment tothe radio network controller. A computer program stored may be providedon a computer readable medium for execution of the foregoing steps.

According to a third aspect of the present invention, a system having aplurality of interconnected radio network controllers, each radionetwork controller comprises a receiver for receiving at the radionetwork controller a measurement report from a user equipment; a deciderfor making a decision at the radio network controller to make a servinghigh-speed downlink shared channel cell change and to make an active setupdate; a preparer for preparing a radio link at a new cell to operateas a serving high-speed downlink shared channel radio link; a sender forsending an active set update message from the radio network controllerto the user equipment, said active set update message includinginformation about the high-speed downlink shared channel cell change;the receiver for also receiving an active set update complete messagefrom the user equipment; and a starter for starting a frame protocol inthe radio link of the new cell.

The system according to the third aspect of the invention may furthercomprise plural user equipment, each user equipment comprising areceiver for receiving said active set update message from said radionetwork controller with a radio link addition or removal to or from theactive set, or both, a checker for checking the active set updatemessage for information about a serving high-speed downlink sharedchannel cell change, a configurer for configuring the user equipment tooperate with a new serving high-speed downlink shared channel cell, anadder and remover module for adding or removing, or both, a radio linkto or from, or both, an active set, and a sender for sending an activeset update complete message from the user equipment to the radio networkcontroller.

According to a fourth aspect of the present invention, a radio networkcontroller, comprises a receiver for receiving at the radio networkcontroller a measurement report from a user equipment; a decider formaking a decision at the radio network controller to make a servinghigh-speed downlink shared channel cell change and to make an active setupdate; a preparer for preparing a radio link at a new cell to operateas a serving high-speed downlink shared channel radio link; a sender forsending an active set update message from the radio network controllerto the user equipment, said active set update message includinginformation about the high-speed downlink shared channel cell change;said receiver for receiving at the radio network controller an activeset update complete message from the user equipment; and a starter forstarting a frame protocol in the radio link of the new cell.

According to a fifth aspect of the present invention, user equipmentcomprises a receiver for receiving an active set update message from aradio network controller with a radio link addition or removal to orfrom the active set, or both; a checker for checking the active setupdate message for information about a serving high-speed downlinkshared channel cell change; a configuration module for configuring theuser equipment to operate with a new serving high-speed downlink sharedchannel cell; an adder and remover module for adding or removing, orboth, a radio link to or from, or both, an active set; and a sender forsending an active set update complete message from the user equipment tothe radio network controller.

According to a sixth aspect of the present invention, a data structureis provided for at least temporary storage in a computer readable mediumfor use in communicating information relating to a serving high-speeddedicated shared channel cell change in an active set update messageover a radio interface between a network element and user equipment.

According to a seventh aspect of the present invention, a method forexecution in network element of a radio communications system comprisesdeciding to make a serving high-speed dedicated shared channel cellchange for user equipment, and communicating information relating tosaid serving high-speed dedicated shared channel cell change in anactive set update message over a radio interface between a networkelement and said user equipment of said radio communication system.

According to an eighth aspect of the present invention, a networkelement comprises means for deciding to make a serving high-speeddedicated shared channel cell change for user equipment and means forcommunicating information relating to said serving high-speed dedicatedshared channel cell change in an active set update message over a radiointerface between said network element and said user equipment.

According to a ninth aspect of the present invention, a method forexecution in user equipment comprises receiving an active set updatemessage having information relating to a serving high-speed dedicatedshared channel cell change, and checking said active set update messagefor said information for configuring said user equipment to operate witha new high-speed shared channel cell.

According to a tenth aspect of the present invention, user equipmentcomprises means for receiving an active set update message havinginformation relating to a serving high-speed dedicated shared channelcell change, means for carrying out an active set update in the userequipment in response to the active set update message, and means forsending an active set update complete message.

According to an eleventh aspect of the present invention, a methodcomprises communicating information relating to a serving high-speeddedicated shared channel cell change in an active set update messageover a radio interface from a network element to user equipment, andcommunicating information concerning completion of said cell change fromsaid user equipment to said network element over said radio interface.

According to a twelfth aspect of the present invention, a systemcomprises means for communicating information relating to a servinghigh-speed dedicated shared channel cell change in an active set updatemessage over a radio interface from a network element to user equipment,and means for communicating information concerning completion of saidcell change from said user equipment to said network element over saidradio interface.

According to a thirteenth aspect of the present invention, a device foruse in user equipment comprises means for checking an active set updatemessage for information concerning a serving high-speed dedicated sharedchannel cell change and means for adding a cell, removing a cell, orboth, from an active set used by said user equipment. The deviceaccording to the thirteenth aspect of the invention may further comprisemeans for configuring said user equipment to operate with anotherserving high-speed dedicated shared channel cell.

According to a fourteenth aspect of the present invention, a device foruse in a network element comprises means for deciding to make a servinghigh-speed dedicated shared channel cell change; and means for preparinga cell to operate as said serving high-speed dedicated shared channelcell.

Because the RRC: ACTIVE SET UPDATE message does not contain HS-DSCHrelated information, which could be utilized for a Serving HS-DSCH cellchange, a separate Radio Bearer Control procedure is needed between theUE and the RNC for carrying out the Serving HS-DSCH cell change. ShouldHS-DSCH related information—applicable to Serving HS-DSCH cell change—beadded to the RRC: ACTIVE SET UPDATE message, an unnecessary Radio BearerControl procedure could be avoided, and the drawbacks of the currentmethod are overcome.

The described functionality will improve the Serving HS-DSCH cell changeprocedure by modifying the existing Active Set Update (ASU) procedure tosupport it. Therefore, signaling of the separate procedure regarding aServing HS-DSCH cell change is avoided and a faster procedure isachieved.

Pros (+) and cons (−) of different implementation alternatives arelisted below:

+ Faster ASU, there is no need to perform Serving HS-DSCH cell changebefore ASU;+ Less messages to be transferred; and+ Smaller transmission break in Serving HS-DSCH cell change or breakfully avoided; but− Longer ASU message

These and other objects, features and advantages of the presentinvention will become more apparent in light of the detailed descriptionof a best mode embodiment thereof, as illustrated in the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a message sequence regarding a combined Active Set Updateand Intra-NodeB serving HS-DSCH cell change, according to the presentinvention.

FIG. 2 shows how FIGS. 2A, 2B, and 2C fit together to altogether show acombined Active Set Update (ASU) and Serving HS-DSCH cell changeprocedure from the point-of-view of the UE, according to the presentinvention.

FIG. 3 shows the functionality in RNC in case of a 1B or 1C event, whichremoves the serving HS-DSCH cell from the active set, according to thepresent invention.

FIG. 4 shows the functionality in RNC in case of 1A event, whichtriggers the serving HS-DSCH cell change to the added cell in the activeset, according to the present invention.

FIG. 5 shows a system comprising plural RNCs with an associated Node Band plural UEs, only one of each type being illustrated, according tothe present invention.

BEST MODE FOR CARRYING OUT THE INVENTION List of Abbreviations (See 3GPPTR 21.905 for a Comprehensive List)

-   3GPP 3rd Generation Partnership Project-   Active Set Set of radio links simultaneously involved in a specific    communication service between a UE and a UTRAN access point-   ASU Active Set Update-   CPICH Common Pilot Channel-   H-RNTI HS-DSCH Radio Network Temporary Identifier-   HSDPA High Speed Downlink Packet Access-   HS-DSCH High Speed Downlink Shared Channel-   HS-PDSCH High Speed Physical Downlink Shared Channel-   HS-SCCH High Speed Shared Control Channel-   Iu Interconnection point between an RNC or a BSC and a 3GPP core    Network-   Iub Interface between an RNC and a Node B-   Iur A logical interface between two RNCs-   MAC-hs High Speed Medium Access Control-   NBAP Node-B Application Part-   Node B A logical node responsible for radio transmission/reception    in one or more cells to/from the User Equipment. Terminates the Iub    interface towards the RNC.-   RB Radio Bearer-   RNC Radio Network Controller-   RNTI Radio Network Temporary Identity-   RRC Radio Resource Control-   UE User Equipment-   UTRAN Universal Terrestrial Radio Access Network

As suggested above, 3GPP specifies Active Set Update being independentfrom Serving HS-DSCH cell change, i.e. HS-DSCH information is nottransferred with Active Set Update but with a separate Radio BearerControl procedure. Should the condition for the Active Set Update becomeeffective simultaneously with the Serving HS-DSCH cell change, twoseparate RRC-procedures must be performed according to the prior art:Active Set Update procedure and Radio Bearer Control procedure. Theapplicable Radio Bearer Control procedure is either Radio BearerReconfiguration, Transport Channel Reconfiguration or Physical ChannelReconfiguration.

According to the present invention, should the combined Active SetUpdate and Serving HS-DSCH cell change be needed, HS-DSCH informationwill be transferred with the RRC: ACTIVE SET UPDATE message. Therefore,a separate Radio Bearer Control procedure is not needed, i.e the sendingof an RRC: (a) RADIO BEARER RECONFIGURATION message, (b) TRANSPORTCHANNEL RECONFIGURATION message, or (c) PHYSICAL CHANNEL RECONFIGURATIONmessage from the RNC to the UE and corresponding response message RRC:(a) RADIO BEARER RECONFIGURATION COMPLETE, (b) TRANSPORT CHANNELRECONFIGURATION COMPLETE, or (c) PHYSICAL CHANNEL RECONFIGURATION isavoided.

A typical use case would be the UE sending an RRC: MEASUREMENT REPORTmessage to the Radio Network Controller (RNC) containing anintra-frequency reporting event 1B: A primary CPICH leaves the reportingrange or 1C: A non-active primary CPICH becomes better than an activeprimary CPICH (for a detailed description of these events see thereference in the paragraph immediately following below). These reportingevents will initiate the Active Set Update procedure and also a ServingHS-DSCH cell change when the radio link in question is the servingHS-DSCH radio link. In these cases, if the RRC: ACTIVE SET UPDATEmessage contained HS-DSCH information, a separate Radio Bearer Controlprocedure would not be needed. This will be seen as a faster proceduresince the sending of two separate RRC-messages between the UE and theRNC is avoided. According to the invention, a combined Active Set Updateand Serving HS-DSCH cell change procedure may also be made applicablewhen the cell is to be added to the active set, that is, when the UEsends reporting event 1A: A primary CPICH enters the reporting range.

Reference is made to Chapter 14 (Specific functions) of 3GPP TS 25.331v6.2.0 (2004-06) (Rel6), particularly Chapter 14.1 (Intra-frequencymeasurements), where Reporting event 1A (A primary CPICH (common pilotchannel) enters the reporting range) is described in Chapter 14.1.2.1,Reporting event 1B (A primary CPICH leaves the reporting range) isdescribed in Chapter 14.1.2.2, and Reporting event 1C (A non-activeprimary CPICH becomes better than an active primary CPICH). is describedin Chapter 14.1.2.3.

According further to the present invention, the following existinginformation elements will be added to the RRC: ACTIVE SET UPDATE message(see TS 25.331 v6.2.0 (2004-06) (Release 6) Chapter 10.2.1 ACTIVE SETUPDATE) as optional information elements (IEs):

1. MAC-hs reset indicator (TS 25.331 10.3.6.24)2. Serving HS-DSCH radio link indicator (TS 25.331 10.3.6.27)3. HS-SCCH info (TS 25.331 10.3.6.36a)

4. New H-RNTI (TS 25.331 10.3.3.14a)

5. HARQ info (TS 25.331 10.3.5.7a).

Assuming the High Speed Shared Control Channel (HS-SCCH) and Hybridautomatic-repeat-request (HARQ) configuration are in most cases not cellspecific information in the UTRAN, typically only the above IEs 1, 2 and4 need to be included in the RRC: ACTIVE SET UPDATE message performingthe Serving HS-DSCH cell change.

When the RNC decides to delete a cell—which is also the current servingHS-DSCH cell—from the active set and initiate the Active Set Updateprocedure, the UE performs an Active Set Update and Serving HS-DSCH cellchange with the one procedure, according to the present invention.

Accordingly, the RNC sends an RRC: ACTIVE SET UPDATE message to the UEand the UE responds after a successful procedure with an RRC: ACTIVE SETUPDATE COMPLETE message. The UE will, in addition to the ASU, alsoupdate HS-DSCH information of the new cell and perform a Serving HS-DSCHcell change. The invention is applicable both to intra-NodeB andinter-NodeB cases (see TS 25.308 v6.1.0 (2004-03) (Release 6) Chapter9.1 Mobility Procedures).

FIG. 1 describes a message sequence with the combined ASU and ServingHS-DSCH cell change procedure with the numerals on the square blocks 1-6to the right side of FIG. 1 corresponding to the numbered paragraphsbelow. The example concerns Intra-NodeB serving HS-DSCH cell change butis not limited thereto.

-   -   1) UE 10 has an active set including two cells 12, 14 under BTS        16: Cell1 12 and Cell2 14. The maximum size of the active set is        2 (see reference numeral 17). As indicated at reference numeral        18, UE 10 is in CELL_DCH state having one PS NRT radio bearer        mapped onto the HS-DSCH transport channel. Cell1 12 is currently        the serving HS-DSCH cell.    -   2) UE sends to the RRC in RNC 20: MEASUREMENT REPORT on a line        22 regarding reporting event 1B: A primary CPICH leaves the        reporting range regarding Cell1 12.    -   3) RNC 20 decides 24 to delete Cell1 12 from the active set and        to perform 26 a change of the serving HS-DSCH cell from Cell1 to        Cell2.    -   4) RNC prepares a radio link at Cell2 14 to operate as a serving        HS-DSCH radio link by exchanging the signals shown on lines 28,        29 and 30. A synchronized procedure is applied.    -   5) RNC sends RRC: ACTIVE SET UPDATE message on a line 32 to UE        10. Unlike the prior art, the message contains HS-DSCH related        information: Serving HS-DSCH radio link indicator and New        H-RNTI. UE deletes Cell1 from the active set, performs Serving        HS-DSCH cell change and acknowledges successful procedure with        RRC: ACTIVE SET UPDATE COMPLETE message on a line 34.    -   6) RNC 20 sends a request on a line 36 to delete radio link at        Cell1 and Cell1 12 then acknowledges a successful deletion        procedure by a signal on a line 38 back to the RNC.

FIG. 2 shows a combined Active Set Update and Serving HS-DSCH cellchange procedure, according to the present invention, from the point ofview of the UE. The procedure is carried out by the functional blocks inthe UE responsible for RRC signalling. Illustrations of these functionalentities can be found for example for both the UE and RRC at TS 25.331(Release 6) v6.2.0: Chapter 4.2. RRC layer model, FIGS. 4.2-1: UE sidemodel of RRC; TS 25.301 (Release 6) v6.0.0: Chapter 5.5, Interactionsbetween RRC and lower layers in the C plane, FIG. 10: Interactionsbetween RRC and lower layers.

The procedure illustrated in FIG. 2 is applicable both to intra-NodeBand inter-NodeB cases. Radio links may be under control of either aServing RNC or a Drift RNC.

-   -   1. An HS-DSCH transport channel is allocated to the UE. The RNC        decides to execute a combined Active Set Update and Serving        HS-DSCH cell change procedure and sends RRC: ACTIVE SET UPDATE        message to the UE as shown in a step 200. This corresponds to        the UE 10 of FIG. 1 receiving the ASU signal on the line 32.    -   2. An Active Set Update procedure is initiated when the RNC        orders a UE in CELL_DCH state to make one of the following        modifications to the active set of the connection: Radio link        addition 202, Radio link removal 206 or Combined radio link        addition and removal 204. These steps 202, 204, 206 can be        understood as the UE 10 deciding exactly which type of order has        been made by the RNC 20.    -   3. In the case where the UE decides the RNC has ordered a Radio        link addition as shown in a step 202, the UE first adds a radio        link to the active set in a step 208. Then the UE proceeds to        the Serving HS-DSCH cell change procedure as follows:        -   i. In a decision step 210, the UE checks the Serving HS-DSCH            radio link indicator IE and New H-RNTI IE. If they are            included, the Serving HS-DSCH cell change procedure is            executed. As illustrated by a step 212, the UE considers the            radio link (RL), determined by the Serving HS-DSCH radio            link indicator, as the serving HS-DSCH radio link. As also            shown in the step 212, the UE uses the value of the New            H-RNTI as the UE identity in the HS-SCCH reception procedure            in the physical layer.        -   ii. If HS-SCCH info IE and HARQ info IE are included, as            determined in a decision step 214, the UE receives the            HS-SCCH(s) according to the HS-SCCH channelization code IE            on the serving HS-DSCH radio link applying the scrambling            code as received in the DL Scrambling code IE. UE also            configures the MAC-hs entity with the number of HARQ            processes indicated in Number of Processes IE and assigns to            each of these HARQ processes ID as indicated in a step 216.        -   iii. If the MAC-hs reset indicator IE is included, as            determined in a decision step 218, the UE resets the MAC-hs            entity as shown in a step 220. A decision step 222 is next            executed to determine if the addition is a combined RL            removal and addition (see section 4 below for the reason for            this).    -   4. In the case where the RNC has ordered “Combined” Radio link        addition and removal, as shown being determined by the UE in the        step 204, the UE first checks the size of the current active set        as shown in a step 226.        -   i. If the size of the active set is below the maximum            allowed, the UE first adds radio link to the active set as            per step 208. Then the UE proceeds to the Serving HS-DSCH            cell change procedure, which is executed according to the            steps described above in sections 3i, 3ii and 3iii as shown            in FIG. 2 with the same reference numerals as described            previously except using the suffix “a”. Finally, after            execution of the step 222 wherein a positive determination            is made that a combined RL removal and addition was ordered            by the RNC, the UE removes the radio link from the AS as            shown in a step 224 followed by a step 290 in which the UE            notifies the RRC in the RNC that the ASU is completed. If it            is determined in the step 222 that a combined RL removal and            addition was not ordered, i.e., the RNC has merely ordered            (in step 202) a radio link addition, the step 290 is            executed directly, without executing step 224.        -   ii. If the decision step 226 determines that the size of the            active set is the maximum allowed, and if the RL, is            determined in a step 228 by the Serving HS-DSCH radio link            indicator IE, is already in the active set, the UE proceeds            to the Serving HS-DSCH cell change procedure, which is            executed according to the above described sections 3i, 3ii            and 3iii. Finally UE removes and adds a radio link as shown            in steps 224 b, 208 b and then step 290 is executed.        -   iii. As shown in the steps below step 226 in FIG. 2 and to            the right of decision step 228, if the size of the active            set is the maximum allowed, and if the RL, determined in the            step 228 by means of the Serving HS-DSCH radio link            indicator IE, is not in the active set, UE removes and adds            a radio link as shown in steps 224 a, 208 a. Then the UE            proceeds to the Serving HS-DSCH cell change procedure, which            is executed according similarly to the above described            sections 3i, 3ii and 3iii as shown in the steps 210 a, 212            a, 214 a, 216 a, 218 a, 220 a and 222 a.    -   5. In the case where the RNC has ordered the Radio link removal        as shown being determined by the UE in a step 206, the UE        proceeds to the Serving HS-DSCH cell change procedure beginning        with a decision step 210 c (similar to decision step 210) and        then proceeds to execute a series of steps 212 c, 214 c, 216 c,        218 c, 270 c which are executed in a manner similar to that        already described in steps 212, 214, 216, 218, 220 in the        sections 3i, 3ii and 3iii and in steps 212 a, 214 a, 216 a, 218        a, 220 a in the sections 4i, 4ii and 4iii above. Finally, the UE        removes the radio link as shown in a step 272.    -   6. At the conclusion of whichever one of the three parallel        procedures shown in FIG. 2 is executed, the UE sends RRC: ACTIVE        SET UPDATE COMPLETE message as shown in the step 290        corresponding to the message signal on the line 34 in FIG. 1.

FIG. 3 shows the functionality from the point of view of the RNC in casean RRC:MEASUREMENT REPORT message is received on the line 22 of FIG. 1reporting event 1B or 1C, which leads to removal of the serving HS-DSCHcell from the active set, as shown in a step 302. See 3GPP TR 25-922 v6.0.1 (2004-04) entitled “Radio Resource Management Strategies” for adescription of events 1A, 1B and 1C. Either synchronized orunsynchronized procedures can be used. Radio links may be under controlof either the Serving RNC or a Drift RNC.

-   -   Optionally the user plane transmission of the RBs mapped to        HS-DSCH is stopped in the Iub frame protocol layer in the        current serving HS-DSCH cell to minimize the amount of data in        the BTS buffer prior to serving HS-DSCH cell change as shown in        a step 304.    -   In case of event 1B the serving HS-DSCH cell is changed to the        new cell with the RADIO LINK RECONFIGURATION NBAP-procedure as        shown in a step 306.    -   In case of event 1C, as shown in a step 308, the new RL is setup        with the RADIO LINK SETUP/RADIO LINK ADDITION NBAP-procedure. If        the new RL in the new radio link set is also the new serving        HS-DSCH cell the RADIO LINK SETUP NBAP-procedure is used to        setup the new serving HS-DSCH cell. If the new serving HS-DSCH        cell is some other RL, the RADIO LINK RECONFIGURATION        NBAP-procedure is used to setup the new serving HS-DSCH cell.    -   RNC sends the ACTIVE SET UPDATE RRC-message on the line 32 shown        in FIG. 1 including the new serving HS-DSCH cell related        information as shown in a step 310 in FIG. 3.    -   RNC receives the ACTIVE SET UPDATE COMPLETE RRC-message on the        line 34 in FIG. 1 from the UE as shown in step 312 in FIG. 3.    -   RNC deletes the removed RL (old serving HS-DSCH cell), with the        RADIO LINK DELETION NBAP-procedure as shown in step 314.    -   The user plane transmission of the RBs mapped to HS-DSCH is        started in the Iub frame protocol layer in the new serving        HS-DSCH cell. Starting could be done for instance according to        any one of the following three alternatives:    -   1) When frame protocol flow control has granted the permission        and the L1 synchronization has been indicated to RNC with the        NBAP:SYNCHRONIZATION INDICATION message as shown in a step 316.    -   2) Immediately when frame protocol flow control has granted the        permission as shown in a step 318.    -   3) When frame protocol flow control has granted the permission        and the defined period of time has elapsed as shown in a step        320.    -   Selection between different methods can be based on information:        -   If the new serving HS-DSCH cell is included in the existing            Radio Link Set, or it is the new radio link which is setup            with NBAP: RADIO LINK SETUP message.        -   If the BTS scheduler is aware of synchronization status of            the RL.

The foregoing steps may be carried out in functional blocks in the RNCthat are responsible for RRC and NBAP signaling. Illustrations of thesefunctional entities may be found for example for the RNC RRC at TS25.331 (Release 6) v.6.2.0: Chapter 4.2. RRC layer model, FIGS. 4.2-2:UTRAN side RRC model (DS-MAP system), FIGS. 4.2-3: UTRAN side RRC model(DS-41 System) NBAP: TS 25.430 (Release 6) v6.1.0: Chapter Iub InterfaceProtocol Structure, FIG. 7: Iub Interface Protocol Structure.Optionally, the functional block responsible for frame protocol isaffected.

FIG. 4 shows the functionality in RNC in case of RRC:MEASUREMENT REPORTmessage is received indicative of event 1A, which triggers the servingHS-DSCH cell change to the added cell in the active set. Eithersynchronized or unsynchronized procedures can be used. Radio links maybe under control of either Serving RNC or Drifting RNC. Thefunctionality follows the functionality in FIG. 3 with similar stepsnumbered similarly except using the suffix “a” as in steps 302 a, 304 a,308 a, 310 a, 312 a, 314 a, 316 a, 318 a, and 320 a, but note that onlythe MAC-d flow(s) is (are) deleted, the RL is not deleted in the oldserving HS-DSCH cell.

FIG. 5 shows a system which should be understood having a plurality ofinterconnected radio network controllers with associated Node B 500 anda plurality of user equipment 10, only one of each type beingillustrated. The RNC/Node B interface (Iub) applies NBAP signalingprotocol and an air-interface (Uu) lies between the NodeB and the UE.Each radio network controller comprises a receiver 502 for receiving atthe radio network controller via Node B a measurement report on the line22 of FIG. 1 from a user equipment and which processes the measurementreport in order to put it in appropriate form for presentation to otherfunctional modules within the RNC. Some of the steps carried out by theblock 502 may for instance includes steps similar to steps 302, 304 or302 a, 304 a of FIG. 3 or FIG. 4, respectively, in whole or in part. Adecider 504 is responsive to the measurement report as processed by thereceiver 502 for making a decision whether to make a serving high-speeddownlink shared channel (HS-DSCH) cell change and whether to make anactive set update. Such a decider can carry out its decision forinstance in conjunction with steps 302, 304 or steps 302 a, 304 a and/orthe steps 24, 26 of FIG. 1. Also included is a preparer 506 forpreparing a radio link at a new cell to operate as a serving high-speeddownlink shared channel radio link. Such a preparer may for instancecarry out steps 306 or 308 of FIG. 3 or step 308 or of FIG. 4, or thosedescribed by the block 4 of FIG. 1. Once the preparer makes the abovementioned preparations it triggers a sender 508 for sending an activeset update message 32 from the radio network controller via Node B tothe user equipment as in the bloc 5 of FIG. 1, the active set updatemessage including information about the high-speed downlink sharedchannel cell change (see step 310 or 310 a of FIG. 3 or 4).Subsequently, the receiver 502 of the RNC 20 receives an active setupdate complete message 34 from the user equipment via Node B whichtriggers a starter 520 to start a frame protocol in the radio link ofthe new cell (see step 312 or 312 a).

One of the plural user equipment 10 is also shown in detail. Each userequipment comprises a receiver 530 for receiving an active set updatemessage 32 from a radio network controller 20 via Node B 500 with aradio link addition or removal to or from the active set, or both. Seestep 200 of FIG. 2A. A checker 532 checks the active set update messagefor information about a serving high-speed downlink shared channel(HS-DSCH) cell change, if any as shown for instance in steps 202, 204,206 of FIG. 2. If such is present, a configuration module 534 configuresthe user equipment to operate with another or a new serving high-speeddownlink shared channel cell as detailed for instance in the steps ofFIG. 2. Once this is carried out, a module 536 for adding or removing,or both, a radio link to or from, or both, an active set, adds a link,removes a link, or does both. Then a sender 538 sends an active setupdate complete message 34 from the user equipment to the radio networkcontroller via Node B as shown in step 290 of FIG. 2. As mentionedpreviously, the receiver 502 in the RNC then triggers the starter 520 tostart the frame protocol in the radio link of the new cell.

It should be understood that some or all of the functional blocks shownin the RNC of FIG. 5 will typically be carried out as codedinstructions, i.e., a computer program embodied in either a computerreadable medium or in an integrated circuit with equivalent dedicatedhardware or a combination thereof. For instance, an integrated circuit550 may be utilized to carry out the functions of the decider 504 andthe preparer 506 of the RNC 20 of FIG. 5. As such, the integratedcircuit 550 may be viewed as means for carrying out the change to thenew HS-DSCH cell within the RNC. Similarly, an integrated circuit 510may be used in the user equipment 10 to carry out the functions of theadder and remover module 536, the configuration module 534 and thechecker module 532. Such an integrated circuit 560 may be viewed asmeans for carrying out the change to the new HS-DSCH cell within the UE.It should also be understood that although the Node B and the UE areshown with a single antenna used by means of a duplexer for both sendingand receiving over the air-interface, there could of course be separatesending and receiving antennas.

Although the invention has been shown and described with respect to abest mode embodiment thereof, it should be understood by those skilledin the art that the foregoing and various other changes, omissions andadditions in the form and detail thereof may be made therein withoutdeparting from the spirit and scope of the invention.

1. (canceled)
 2. A method performed by user equipment, comprising:receiving an active set update message from a radio network controllerwhile communicating with the radio network controller in a currentserving high-speed downlink shared channel (HS-DSCH) cell, the activeset update message comprising a first part of information configured toorder the user equipment to make one or more of the followingmodifications to an active set of a connection: adding a radio link tothe active set, and removing a radio link from the active set; modifyingthe active set according to the first part of information of the activeset update message; checking whether the received active set updatemessage includes a serving HS-DSCH indicator indicating a new servingHS-DSCH radio link of a new serving HS-DSCH cell and a new HS-DSCH RadioNetwork Temporary Identifier (New H-RNTI); and responsive to thereceived active set update message including the serving HS-DSCHindicator and the New H-RNTI, performing a serving HS-DSCH cell changefrom the current serving HS-DSCH cell to the new serving HS-DSCH cell,with the new serving HS-DSCH radio link indicated by the serving HS-DSCHindicator in the received active set update message as a serving HS-DSCHradio link of the new serving HS-DSCH cell.
 3. The method of claim 2,further comprising: responsive to the active set update messageincluding the serving HS-DSCH indicator and the New H-RNTI, using theNew HRNTI in the received active set update message as an identity ofthe user equipment for HS-SCCH reception from the new serving HS-DSCHcell.
 4. The method of claim 2, further comprising: responsive to thereceived active set update message also including a MAC-hs resetindicator, resetting a MAC-hs entity.
 5. The method of claim 2, furthercomprising: checking whether the received active set update message alsoincludes HS-SCCH information and HARQ information; responsive to thereceived active set update message also including HS-SCCH information,receiving HS-SCCH according to a HS-SCCH channelization code provided bythe HS-SCCH information; and responsive to the received active setupdate message also including HARQ information, configuring the MAC-hsentity according to a number of HARQ processes provided by the HARQinformation.
 6. The method of claim 2, further comprising: after thesteps of modifying the active set and performing the serving HS-DSCHcell change, sending an active set update complete message to the radionetwork controller.
 7. The method of claim 2, wherein, responsive to thefirst part of information ordering radio link addition, the step ofmodifying the active set to add a radio link is performed prior toperforming the serving HS-DSCH cell change.
 8. The method of claim 7,wherein, responsive to the first part of information also ordering radiolink removal and to the size of the current active set being below themaximum allowed, the step of modifying the active set to remove a radiolink is performed after performing the serving HS-DSCH cell change. 9.The method of claim 2, wherein, responsive to the first part ofinformation ordering radio link removal, the step of modifying theactive set to remove a radio link is performed after performing theserving HS-DSCH cell change.
 10. The method of claim 2, wherein,responsive to the first part of information ordering both radio linkaddition and removal and to the size of the current active set being atthe maximum allowed, the step of modifying the active set comprisesremoving a radio link and then adding a radio link, both performed priorto performing the serving HS-DSCH cell change.
 11. Mobile communicationsuser equipment, comprising: a receiver configured to receive an activeset update message from a radio network controller; and a processorconfigured to: check the active set update message for a first part ofinformation configured to order the user equipment to make one or moreof the following modifications to an active set of a connection: Radiolink addition and Radio link removal; modify the active set of theconnection according to the first part of information of the active setupdate message; check whether the active set update message includes aserving HS-DSCH indicator indicating a new serving HS-DSCH radio link ofa new serving HS-DSCH cell and a new HS-DSCH Radio Network TemporaryIdentifier (New H-RNTI); and responsive to the received active setupdate message including the serving HS-DSCH indicator and the NewH-RNTI, perform a serving HS-DSCH cell change from the current servingHS-DSCH cell to the new serving HS-DSCH cell, with the new servingHS-DSCH radio link indicated by the serving HS-DSCH indicator in thereceived active set update message to be used as a serving HS-DSCH radiolink of the new serving HS-DSCH cell; wherein the receiver and processorare further configured so that the receiver receives the active setupdate message while the user equipment communicates with the radionetwork controller in a current serving high-speed downlink sharedchannel (HS-DSCH) cell.
 12. The user equipment of claim 11, wherein theprocessor is further configured to: responsive to the active set updatemessage including the serving HS-DSCH indicator and the New H-RNTI, usethe New HRNTI in the received active set update message as an identityof the user equipment for HS-SCCH reception from the new serving HS-DSCHcell.
 13. The user equipment of claim 11, wherein the processor isfurther configured to: responsive to the received active set updatemessage also including a MAC-hs reset indicator, reset a MAC-hs entity.14. The user equipment of claim 11, wherein the processor is furtherconfigured to: check whether the received active set update message alsoincludes HS-SCCH information and HARQ information; responsive to thereceived active set update message also including HS-SCCH information,receive HS-SCCH according to a HS-SCCH channelization code provided bythe HS-SCCH information; and responsive to the received active setupdate message also including HARQ information, configure the MAC-hsentity according to a number of HARQ processes provided by the HARQinformation.
 15. The user equipment of claim 11, wherein the processoris further configured to: after the steps of modifying the active setand performing the serving HS-DSCH cell change, send an active setupdate complete message to the radio network controller.
 16. The userequipment of claim 11, wherein the processor is configured to modify theactive set to add a radio link, responsive to the first part ofinformation ordering radio link addition, prior to performing theserving HS-DSCH cell change.
 17. The user equipment of claim 16, whereinthe processor is configured to modify the active set to remove a radiolink, responsive to the first part of information also ordering radiolink removal and to the size of the current active set being below themaximum allowed, after performing the serving HS-DSCH cell change. 18.The user equipment of claim 11, wherein the processor is configured tomodify the active set to remove a radio link, responsive to the firstpart of information ordering radio link removal, after performing theserving HS-DSCH cell change.
 19. The user equipment of claim 11, whereinthe processor is configured to modify the active set to remove a radiolink and then add a radio link, responsive to the first part ofinformation ordering both radio link addition and removal and to thesize of the current active set being at the maximum allowed, both priorto performing the serving HS-DSCH cell change.